Page 270 - needle bearings

Thrust roller bearings
NTN

Bearing accuracy Bearing fit in bearing ring
The respective dimensional accuracy, profile accuracy Table 2 shows the tolerances for fitting of the thrust
and running accuracy of thrust cylindrical roller bearings bearing rings (AS, WS and GS) on shaft or in housing.
811, 812 and 893 are as shown in Table 4.4 of Section 4
"Bearing Accuracy" (page A-28).
The thrust roller and cage assemblies (AXK, K811, Table 2 Bearing ring fit in shaft and housing
K812, K893) are machined with dimensional tolerance Bearing ring Shaft Housing
E11 for the bore diameter (De1) (E12 for bearing number
Series AS h10 H11
with T2 code) and with dimensional tolerance c12 for the
outer diameter (De) of Type AXK and a13 for the Series WS h6 ʵʵ
diameter (De) of K811, K812 and K893. Series GS ʵʵ H7

Raceway surface requirements:
Where the plane portion of a shaft/a housing is used as Mounting related dimensions
the direct raceway surface of thrust roller and cage
The dimensions related to fitting of WS and GS bearing
assembly, the raceway surface must meet the rings on shaft and in housing are as described in
requirements specified as a guideline in Table 1.
applicable Dimensions Table.
The fitting surface of AS bearing ring must be flat and
have the rigidity sufficient to support thrust load
Table 1 Raceway surface requirements
throughout its entire surface.
Characteristics Specified requirements
Perpendicularity (Max) IT6 (IT4)
Surface roughness 0.2a
Surface hardness HRC58ʙ64
Effective hardened layer depth Refer to Formula (7.1) on page A-39.
Reference : The parenthesized value shall be applied for high running accuracy.

Cage guiding
The thrust roller and cage assemblies (AXK, K811,
K812 and K893) must be guided at either the bore side
(shaft side) or the outer surface side (housing side) for in-
running centering.
In general, the bore-side guide of low relative speed
against the cage is mostly used. It should be used
particularly for high speed running. The dimensional
tolerances for shaft and housing, when the cage is guided
thereby, shall be h8 for shaft diameter (bore guide) and
H9 for housing bore diameter (outer surface guide)
respectively, which of the guide surface shall be fine-
finished by grinding.

B-208